Selector for automatic firearms



Jan 30 1951 J. L.. LocHHEAD SELECTOR FOR AUTOMATIC FIREARMS Filed' July 29, 1948 gmac/nto@ vided somewhat above the axis' of pin I9;

Patented Jan. 30, 1,951

UNITED STATES -Mem osi-"ice (Granted under the act or'Marelr 3,. 1883;: as amended: April 30; 1928; 370 0. G'..75,7.).

2i Claiins The invention described hereinAv may be-manuffactured and usedl byor for the. Governmentv forv governmental' purposes. withoutl the payment of any royalty thereon.

lhi'srinventiorr relates to'. a: selector for1 selece t'wely positioning` the. fire control" mechanism of azefirearm' forA semilautomaticz or full-.automatic fitter Thisisa .divisional application: of my copending application for; Fire?. Control Mechanism, Serial` No; '101,145z'1iled @ctoberrflr1946;;now'abandoned;

particular; object.' of' this' invention is: to; provide;` a fire control: mechanism: for; a rearm: of. ther typefknown. as the; U.` Si Carbine; cal'.- .305- M1'` whereby?either semi-automatic or fullautomatic firefcambe-selected at will:y

The: specifici nature; of: the invention as. well asother;v objects and advantages: thereof will; clearlyappear'from a descriptionw of 'a preferred. embodi ment; as: shown; inthe accompanying; drawings which Fig, 1: isan enlarged detail viewfof theselector andAv trigger; mechanism shown: set for semiautomatic;y rewith theVV trigger inf. the pulled position..r

Figi.. 2-isanexploded'. view 'of therelated-.parts of. the'` fire control' mechanism'.` and-1 the fire. selector..

Fig;,3 is a-viewf similar.. to'fE-ig. 1 but showing` the mechanism set for full-automatiere..

There is'fshown' inassembled relation in Figs. 1 and 3 a trigger guard 4 of the U. S. Carbine,

, cal. .30 M1 embodying thisI invention. The fire control mechanism. is mountedv in trigger guard fand mai'nl'y comprises a hammer IB .a trigger I6, a primary sear I1 and a secondary sear I8. Hammer I? is?v pivotally` mounted' approximately in the. center of trigger guard 4 by a transverse pin ISIl.` Hammer I5 is arranged to be rotated: forwardly'in a' clockwisedirection by a spring biased; plunger The forward end of plunger v2II` lies: within 'asuitable slot' in' hammer I5 pro'- A sear; notch` 2I -isA providedH on the bottom surface off hammer' I5"amdar1"integral` outwardly' projecting sear lugv 2'7lissproviiiexcorr1the right side of hammer I5.

. Trigger.. Ifis pivotally, mountedcn a transverse pim-33.in..trgger guard 4'. somewhat to-the rear of hammer I5 as shown in Figs. 1 and 3. Anotch 34 is provided in the rear of trigger I6 which is engaged by a trigger spring 35. Spring 35 lies within a substantially horizontal hole 3E in the rear of the trigger guard 6 and such spring is provided to yieldingly maintain trigger I6 for- 2.: wardly in such a positionY thatfprimary seal:` lili engages hammer I5? forwardly projectingrinategral lug 31- is provided onl theleftsidefof- 'trigger' ISand' a cam surface- 3'8* formedl on iopofisucl-r f lug' slopes downwardly: substantially as shown Figi' Zf to-provide-meansfforf raising primary sears' I1'aswill?belaterdescribed @n the-'bottom of trigger I'61 thereL is: providedVVA al horizontal hole MIL inwhi'chris insertedionel end of`a spring; 41'.. integral l'upstfanding lug- Sili's providedy on'- therear of" the'top surface-oftrigger IISfora purpose bei-later described'.

Primary' sea-r If'I is providedr`witn. air elongated hole i2-Torf mounting such sean on piir'33 .withii'xe` av bifurcated portion of trigger r6.1 integral; downwardly* projecting lug 43 is providedap..`` proximately in the centerf of primary Sear` Ivlran'ri a' rearwardly facing; shallow, cylindrical recess-1 M- (Fig. 1) i's provided?. in the-reairofl'sucl'r luga inlwhichthe other endoisearV springl iszseated. Spring M is provided to maintain. the. sear- I afbrward' position when the trigger" I'6fis'inzthef: ferwardiposition".H nint'egralfarm d5isprovid'ed: on1A ther left'side' of primary sear IIy 'as' show-nm Fig. 2. Such arm projects forwardly in a sube stantially h'ori'zontal'planef and is provided' with ay downwardly'projecting lug 4E atitheextreme forward endof" such. arm. The' lowerV rear sur.; faceof arm 45 is sloped downwardly andi for'- Wardly as shown at 4I to provide-a surfaceawhich' is' engaged by v surface 337 provided on. trigger I6" as will loe-later described. Lugll'fof'armIoirV primary'sear-Y Eil-"projects downwardlyiso'that it can-J Ideengaged? by: a selector' 4B.

Secondary searf V31 isla lever-like member and' the forward endof suchf sear'isfpl'aced within a suitable slot' 2&7 onf thevv topi of trigger guardi? 4.. transverse pin 'E5 passingtlirough slot`2f4wis provided to pivot'ally mount1se'condary'sear' I8?. A-suitable notch 2$lisfpr-ovided`on the* rear end? ofya secondary Sear ISwhi'ch' is shaped to: engage tlie frwardcornerofsearlugf 22t on" the hammer t5. Arr integral? upstanding vertical l'ugfrz?! is; provided? approximately in the" center of secondiary-sear I8i Tliet'opiof'such lug isf disposed-Tat" right'angles todormat'ang 28"." Such tang is alsopref'erably"obliquelyf disposed so-` that suchV tang' willi projfect'finto the pathfof al kol'i'f4v (not'showm for af purpose to beY describ'edll later: Secondary- Searr Iffisearranged' te be raisediupwardly by al: spring-biasedfplunger 31? housedx within a verticali hole 32 somewhat to the rear of a recess I2 in trigger guard Thus spring biased plunger 3| raises secondary sear IB upwardly so that notch 26 on such Sear will engage lug 22 of hammer I5.

The selector 48 comprises a cylindrical studlike portion 49 and an integral knob 50. A transverse slot I is provided on the cylindrical portion 49 which cooperates with lug 46 of primary sear Il to produce semior full-automatic fire as will be later described. Selector 48 is mounted in a transverse hole 52 provided in the lower forward portion of trigger guard 4. The selector 48 is arranged to be yieldingly retained within hole 52 by a spring biased plunger 53. Plunger 53 is mounted in a horizontal hole 54 in the lower forward portion of trigger guard 4 which oommuncates with transverse hole 52. A magazine catch I3 lies within a transverse slot 55 provided in the forward end of trigger guard 4 as shown in Figs. 1 and 3. Catch I3 is mounted in operative position by a spring biased plunger 56 placed within hole 54. Plungers 53 and 56 are biased in opposite directions by a spring 51.

To obtain semi-automatic fire, selector 48 is rotated so that the bottom of slot 5| lies in a horizontal plane with the lug 46 of sear arm 45 in the forward position as shown in Fig. 1. Rotation of selector 48 is effected by turning knob 59. Spring biased plunger 53 then yieldingly engages one of two radially spaced holes 53 and 59 provided about the periphery of cylindrical portion 49 of selector 48. Thus selector 48 is yieldingly held in position for semi-automatic re. The firearm (not shown) is then charged in the usual mannenand the bolt of the firearm (not shown) strikes the top of hammer I 5, thereby rotating such hammer in a counter-clockwise direction as shown in Fig. 1, whereupon notch 26 on the rear of secondary sear I8 engages lug 22 of hammer I5. The bolt (not shown) is then permitted to return to the breeched position thereby depressing tang 28 of sear I8 and forcing notch 26 out of engagement with lug 22. As trigger I6 is in the forward position, the front end of primary sear I'I will engage sear notch 2I on hammer I 5 before such hammer can rotate into contact with a firing pin (not shown) even though secondary sear I8 has released hammer Automatic fire is readily obtained when selector 48 is turned so that the bottom of slot` 5I is in a substantially vertical position as shown in Fig. 3. When in such position, forward movement of primary sear Il is blocked. The reason for this will be presently described. The firearm with selector 48 set for automatic fire is charged in the same manner as that described for semiautomatic fire. With trigger I6 in the forward or normal position, the forward end of primary sear I7 is in engagement with sear notch ZI on the bottom of hammer I5. As selector 48 is now in position for automatic nre, such selector holds sear arm 45 in a rearward position against the bias of spring 4I so that the forward end of elongated hole 42 is maintained in contact with pin 33. Hence the rear end of primary sear II rests on top of trigger lug 60 as shown in Fig. 3. Surface 38 on trigger lug 3l' mates With surface 4l provided on the rear of sear arm 45 and thereby,v imparts the pivotal movement of trigger I6 upon release thereof to primary sear Il in order to withdraw sear lug 46 out of engagement with the bottom surface-of slot 5I and permit sear Il to be biased forwardly by spring 4I into engagement with hammer notch 2| as hammer I5 is released by secondary sear I8 thus effecting cessation of automatic i'lre.

Sear Il is readily blocked to provide a safe position when transporting the firearm in a loaded condition by rotating selector 48 so that lug 46 of arm 45 rests on the arcuate surface of stud 49. When in such position sear I'I can not be disengaged from hammer I5. Selector 48 is yieldingly retained in such position by plunger 53 which engages a suitable recess (not shown) in stud 49.

I claim:

l. In a firearm having a hammer pivotally mounted for movement between a cocked and a ring position, a spring-biased pivotal sear normally arranged to engage and retain the hammer in the cocked position, a pivotal trigger for disengaging the sear from the hammer, and a pivot pin jointly mounting the trigger and the sear for independent pivotal movement, the sear having an elongated pivot hole for permitting longitudinal reciprocable movement thereof relative to the trigger, the improvement comprising an elongated arm extending forwardly from the side of the sear and terminating in a downwardly projecting lug, a rotatable cylindrical selector member having a rectangular transverse slot therein arranged to cooperate with said sear lug, detent means for releasably securing said selector member in either of two positions comprising, a semiautomatic position wherein said slot -permits the sear to move forwardly upon release of the hammer for re-engagement therewith, and a full automatic position wherein the bottom surface of said slot lblocks the sear from moving forwardly and prevents re-engagement thereof with the hammer until the trigger is released, and means on the trigger for pivoting the sear to withdraw said projecting lug thereon out of said slot when the trigger is released during automatic fire.

2. The structure defined in claim 1 wherein said last-mentioned means comprises a forwardly projecting lug portion on the trigger, said lug portion having a forwardly and downwardly sloped top surface, and an oppositely sloped surface on the underside of said elongated sear arm arranged to mate with said sloped surface on said trigger lug portion when the sear is blocked by said selector from moving forwardly relative'to the trigger.

' JOHN L. LOCHHEAD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Germany June 21, 1933 

